Maybe a driver, maybe ram....??
Ram can fail at any time and many times it's hard to detect because a certain memory area that is failing to hold a charge may work much of the time and then after a while start acting up and causing errors. There are memory test utilities that will detect errors MemTest86 boots from a USB flash drive or CD and tests the RAM in your computer for faults: http://www.memtest86.com/
Try that and then go from there....